Intaglio printing generally relates to the art of printing by presenting a design or figure carved or engraved below the surface of a printing plate or cylinder. Ink is then applied to the intaglio printing plate or cylinder and the excess ink is removed by any number of devices including rollers and doctor blades.
For example, U.S. Pat. No. 4,499,825 discloses an ink wiping roller which is rotably supported with its lower portion emersed in a cleansing liquid.
Another wiping arrangement is illustrated in U.S. Pat. No. 3,333,535 which shows the use of a deflector blade and a doctor blade in combination with a plate cylinder whereby ink not removed by the deflector blade is removed from the surface of the plate by the doctor blade.
Moreover, U.S. Pat. No. 4,009,657 teaches the use of a doctor blade and a prewipe blade which comprises a thin flexible blade that extends generally vertically towards the intaglio roll.
Furthermore, U.S. Pat. No. 4,676,157 discloses a wiping apparatus for an intaglio printing machine which has a first roller in rolling contact with a plate cylinder and which is driven in the same rotational direction as the plate cylinder, and a second wiping roller which is in rolling contact with the first wiping roller and which is frictionally driven in the same direction as that of the first wiping roller.
Finally, U.S. Pat. No. 1,927,056 relates to a method and mechanism for cleansing the ink surface of engraving plates and more particularly to the method of removing ink from non-printing surfaces of the plate.
Printing speed or the speed of rotation of printing cylinders of prior art printing presses is limited by a number of factors including the likelihood of generating ink voids and ink skipping due in part to inefficient wiping and application of ink to the printing cylinder by the prior art wiping devices and the creation of bubbles by turbulence which are sheared by the prior art wiping devices. The likelihood of generating ink voids and ink skipping increases particularly when lighter ink tones are required on the printed material.
Furthermore, the prior art wiping apparatus used in the printing industry present relatively complicated structures which are prone to be maintained to either remove excess ink accumulated in the vicinity of the wiping apparatus or to correct ink voids or skipping which develop on the surface of the printing cylinders due to the high rate of rotation of the printing cylinders during the printing process.
It is an object of this invention to present an improved prewipe device which is simple in construction and has improved wiping characeristics.
The broadest aspect of this invention relates to a device for wiping ink from a cylindrical printing surface, said device being formed from a single piece of flexible material and folded to form a pair of spaced apart legs joined by a deformable folded portion, and a stiffener disposed between said legs for maintaining said legs in said spaced apart relationship, said folded portion adapted to press against and conform to a segment of said cylindrical printing surface so as to wipe ink from said printing surface as said folded portion moves over said printing surface.
Another aspect of this invention relates to a device for wiping ink from a cylindrical printing surface, said device being formed from a single piece of flexible material and folded to form a pair of legs joined by a deformable folded portion, and sitffener disposed between said legs for maintaining said legs in the said spaced apart relationship so as to present a resilient core defined by said folded portion, said folded portion adapted to press against and conform to a segment of said cylindrical printing surface so as to wipe ink from said printing surface as said folded portion moves over said printing surface.
It is another aspect of this invention to provide apparatus for distributing ink onto a rotating intaglio printing cylinder for subsequent transfer to an absorbent fibrous web in contact, with said intaglio cylinder, comprising; an ink reservoir disposed below said intaglio printing cylinder, whereby ink in said ink reservoir is adapted to contact the lower portion of said rotating intaglio cylinder and to adhere onto the surface of said cylinder; a prewipe device positioned axially across the surface of said cylinder and above said reservoir, said device being formed from a single piece of flexible material and folded to form a pair of spaced apart legs joined by a deformable folded portion, and a stiffener adapted to be placed between said legs for maintaining said legs in said spaced apart relationship so as to present a resilient core defined by said folded portion, whereby said folded portion defining said resilient core is adapted to press against and conform to a segment of said printing cylinder so as to uniformly apply said ink to said surface of said intaglio cylinder and to wipe a portion of excess ink from said printing cylinder as said folded portion moves over said printing cylinder; a doctor blade positioned against said intaglio cylinder and above said prewipe device for removing substantially any excess ink on the surface of said intaglio cylinder.
Yet another aspect of this invention relates to an apparatus for distributing ink onto a rotating intaglio printing cylinder for subsequent transfer to an absorbent fibrous web in contract with said intaglio cylinder comprising: an ink reservoir disposed below said intaglio printing cylinder, whereby ink in said ink reservoir is adapted to contact the lower portion of said rotating intaglio cylinder and to adhere onto the surface of said cylinder; a prewipe device positioned axially across the surface of said cylinder, said device being formed from a single piece of felt material disposed horizontally above the axis of said intaglio cylinder, said felt material folded to form a pair of legs joined by a deformable folded portion, said legs maintained in spaced apart relationship by a stiffener disposed between said legs so as to present a resilient core defined by said folded portion, said folded portion adapted to press against and conform to a segment of said printing cylinder to uniformly apply said ink to said surface of said intaglio cylinder and to wipe a portion of said excess ink therefrom as said folded portion moves over said printing surface; a doctor blade positioned against said intaglio cylinder and above said prewipe device for removing substantially any excess ink on the surface of said intaglio cylinder.
It is another aspect of this invention to provide a method for applying ink to an intaglio cylinder for subsequent transfer to a paper web comprising the steps of: applying ink to an intaglio cylinder rotating about its axis; folding a single piece of flexible material to form a pair of spaced apart legs joined by a deformable folded portion maintained in said spaced apart relationship by a stiffener disposed between said legs; applying said folded portion against said cylinder so that said folded portion conforms to a segment of said cylinder so as to wipe said ink from said cylinder as said folded portion moves over said cylinder; removing substantially all excess ink from the surface of said intaglio cylinder by a doctor blade positioned against said intaglio cylinder and above said flexible materials; transfering ink from said intaglio cylinder to said paper web.